Question

Using AspectJ, I can get hold of the singleton instance of an aspect using the aspectOf() method:

MyAspect aspect = Aspects.aspectOf(MyAspect.class);

// now perform post-application startup initialisation, eg:
aspect.setLogService(logging); 

Is there a way to get a list of all of the aspects in my running Java application? I’m using AspectJ 1.6.7 with load-time weaving, but can upgrade versions if required.

A list of all of the aspects in my application will allow me to inject dependencies into them at startup.

Answer 1

A rather hackish solution, but a solution nonetheless: manually load the aop.xml file from the classpath and parse it to get the aspect classnames:

final Enumeration<URL> urls =
  getClass().getClassLoader().getResources("META-INF/aop.xml");

final Collection<String> aspectNames = new ArrayList<String>();

for (final URL url : urls) 
{
    final Stream xml = url.openStream();

    final DocumentBuilderFactory docBuilderFactory = 
      DocumentBuilderFactory.newInstance();
    docBuilderFactory.setValidating(false);
    docBuilderFactory.setNamespaceAware(false);

    final XPath xpath = XPathFactory.newInstance().newXPath();
    final Document aspectXml = docBuilderFactory.newDocumentBuilder().parse(xml);
    final XPathExpression selector = xpath.compile("//aspect/@name");

    final NodeList matches = 
      (NodeList) selector.evaluate(aspectXml, XPathConstants.NODESET);

    for (int i = 0; i < matches.getLength(); i++) 
    {
        aspectNames.add(matches.item(i).getNodeValue());
    }    
}

Then aspect instances can be fetched like so:

for (final String className : aspectNames) 
{
    final Class<?> aspectClass = Class.forName(className);
    final Object aspect = Aspects.aspectOf(aspectClass);

    // finally (!) do the initialisation on the aspect itself:
    aspect.setLogService(logging);
}